1. Field of the Invention
The present invention relates to a video and audio recording and reproducing apparatus and method, and more specifically, to a video and audio recording and reproducing apparatus and method in which video data and audio data are stored independent of each other in different recording media.
2. Description of the Related Art
In recent years, with multichannelization of information supply with the spread of CATV (cable television) or the like, there has been an increasing demand for means for simultaneously recording and/or reproducing a plurality of video and audio data using a single video and audio data recording and reproducing apparatus, different from conventional VCR (video cassette recorder). To meet the demand, an apparatus called video server (also referred to as AV (audio and/or video) server) which records and reproduces video and audio using a random accessible (nonlinear accessible) recording medium such as hard disks has been spreading.
Generally, due to requirements for picture and sound of high quality, a video server in a broadcasting station is required to transfer data at high rates and to have large capacity to record long-hour data. Therefore, attempts have been made to increase data transfer rate and to enlarge capacity by using a data recording and reproducing apparatus including a plurality of hard disk (hereinafter referred also to as xe2x80x9cHDxe2x80x9d) units to store video and audio data and to be able to perform parallel processing, or to ensure reliability even if one of the HD units has failed, by recording parity data. Thus, a multichannel video server has become feasible which is capable of coping with a variety of modes of use such as construction of systems including VOD (video on demand) and NVOD (near video on demand), by distributively recording material data composed of a plurality of audio and video data and simultaneously performing multichannel sending or reproducing of the same with staggering reproduction time, even if the number of channels required is different depending on the contents or broadcasting modes of programs to be provided by the broadcasting station.
A data recording and reproducing apparatus used in such a video server employs an RAID (Redundant Arrays of Inexpensive Disks) technique using a plurality of hard disk drives (hereinafter referred to as xe2x80x9cHDDsxe2x80x9d) including a plurality of HDs, as proposed in an article published by Petterson et al. in 1988 (xe2x80x9cA Case for Redundant Arrays of Inexpensive Disks (RAID)xe2x80x9d, ACM SIGMOND Conference, Chicago, Ill., Jun. 13, 1988).
In the above article, RAID is classified into five groups, i.e., RAID-1 to RAID-5. RAID-1 is a format in which the same contents are written into two HDDs. RAID-3 is a format in which input data are divided into portions of a fixed length and recorded in a plurality of HDDs, and parity data which is the exclusive OR of data blocks corresponding to each other for each of the HDDs are written into the other HDD. Furthermore, in RAID-5, unit of division (block) of data is enlarged to record one division unit of the data into one HDD as a data block, and the exclusive OR (parity data) of the data blocks corresponding to each other for each of the HDDs is recorded on the other HDD as a parity block, then the parity block is distributed to all the HDDs. For the other RAIDs, please refer to the above article.
On the other hand, in a conventional video and audio recording and reproducing apparatus to record and reproduce video and audio data, audio data have been considered to be ancillary to video data and the video and audio data have been recorded unitedly.
However, in case of broadcasts relating to news for example, audio data and video data are not always united. There are many occasions in which one and the same video is broadcast in combination with different audio data, e.g., in different languages, of a plurality of audio channels.
Even in the video server using non-linear accessible recording media described above, audio data have been so far processed as part of video data, and therefore it has been impossible to combine one and the same video with a plurality of audio channels or to substitute the audio data for each channel in real time.
Therefore, an object of the present invention is to provide a video and audio recording apparatus and method in which audio data are recorded in a different recording medium independent of video data.
Another object of the present invention is to provide a video and audio recording apparatus and method in which, for respective audio data of a plurality of audio channels, a plurality of identical data (logical volume) are recorded on different recording media.
More specifically, an object of the present invention is to provide a video and audio recording and reproducing apparatus and method using RAID technique in which a plurality of identical logical volumes are recorded on different recording media, and which enables combination of the same video data with different audio data.
A video and audio recording and reproducing apparatus according to the invention is to record and reproduce video data and audio data by using nonlinear accessible recording media, which comprises a video data recording unit for writing and reading video data by using a nonlinear accessible recording medium in which video data are stored, and an audio data recording unit for writing and reading audio data corresponding to each of a plurality of audio data channels, independent of said video data recording unit, by using a nonlinear accessible recording medium in which audio data are stored and which is different from said recording medium in which video data are stored.
In this video and audio recording and reproducing apparatus, writing and reading of video data are performed by the video data recording unit by using a nonlinear accessible recording medium in which video data are stored, and, writing and reading of audio data corresponding to each of a plurality of audio data channels are performed by the audio data recording unit, independent of said video data recording unit, by using a nonlinear accessible recording medium in which audio data are stored and which is different from said recording medium in which video data are stored.
The video and audio recording and reproducing method according to the invention is a method for recording and reproducing video data and audio data by using nonlinear accessible recording media, by which writing and reading of video data are performed by using a nonlinear accessible recording medium in which video data are stored, and writing and reading of audio data corresponding to each of a plurality of audio data channels are performed, independent of said video data, by using a non-linear accessible recording medium in which audio data are stored and which is different from said recording medium in which video data are stored.
According to the video and audio recording and reproducing apparatus or method of the invention, audio data can be stored in a different recording medium independent of video data, so that it becomes possible to store the video data in redundant structure independent of the audio data, and to combine one and the same video data with different audio data.
Other and further objects, features and advantages of the invention will become fully apparent from the following description.